This invention relates to a positive displacement motor that can be used, among other applications, for drilling oil and gas exploration holes, oil wells and directional holes for different purposes.
In some cases of exploration holes it is necessary to produce drilling power right on the drilling bit that may be operating deep in a hole that may be curved (not straight). In such cases a positive displacement motor is required, usually powered by pressurized fluid/gas mixture pumped from the surface. The motor transforms mainly hydrostatic energy of the fluid/gas mixture into rotary motion being used to power the drilling bit in the hole.
Prior positive displacement motors for drilling exhibit a few disadvantages. Some of them require a universal joint that has to carry all drilling power since the motor itself performs a complex motion (two circular motions combined). Prior motors may contain polymer parts which would wear out thus reducing duration of drilling runs. Other disadvantage of the prior motors is substantial length of the motor required to generate a sufficient power for the drilling bit. Such lengthy motors may be sensitive to high bending moments that may occur under some drilling conditions.